The present invention relates to a recording unit and an image recording apparatus. More particularly, the invention relates to the recording unit having an electrostatic latent image carrying means and a developing means provided pivotable to a developing position in which the electrostatic latent image carrying means is exposed to an image transfer portion and to a blockage position where the carrying means is shut-off from the image transfer portion. The invention also relates to an image recording apparatus which receives therein the recording unit and which moves the developing means to the developing position and the blockage position.
In a conventional image recording apparatus of an electrophotographic type, intricate maintenance is required such as supply and waste of developer agent and cleaning to a charger. To obviate this intricacy, a recording unit has been provided which integrally accommodates therein a photosensitive drum serving as electrostatic latent image carrier, developer means, a cleaner and a charger. The one integral unit undergoes replacement on a unit basis so as to facilitate maintenance work.
In the conventional recording unit however, since a photosensitive drum portion confronting the charger is exposed to an atmosphere, the photosensitive drum may be damaged or contaminated at the time of disposal of sheet jamming and the unit replacement work. Further, the drum is subjected to degradation due to drum fatigue attendant to external light irradiation to the exposed drum portion.
In order to avoid this drawback, a movable protection cover is provided to the recording unit, where the protection cover is moved away from an image transferring section at the time of assembly of the recording unit to the image recording apparatus. Still however, the provision of the exclusively used protection cover to the recording unit leads to increase in mechanical components, and further, a space is required within the image recording apparatus so as to allow the protection cover to move to its retracted position relative to the recording unit. Furthermore, untransferred developer agent remaining on the photosensitive drum may adhere onto an inner surface of the protection cover to cause contamination, and the image recording apparatus may be soiled with the untransferred developer agent at the time of retraction of the protection cover.